The present invention relates to a pneumatic tire, further in details, relates to a pneumatic tire promoting an outlook by changing reflection of light at a tire outer surface.
Generally, it is important in view of promoting a commercial value of a pneumatic tire to promote an outlook of a pneumatic tire, particularly, an outlook of a side portion and various proposals have been made in background arts.
For example, JP-A-07-096719 (KOKAI) (reference 1) proposes a pneumatic tire providing a nylon film layer on an outer side of a side wall rubber layer in order to promote an outlook of the tire as well as a weather resistance thereof. Further, JP-A-03-292205 (KOKAI) (reference 2) proposes a pneumatic tire laminating a thin film comprising polyethylene of an ultra high molecular weight on a side wall surface in order to promote an outlook while providing an ozone crack resistance.
JP-A-2000-142026 (KOKAI)(reference 3) discloses that in order to promote an outlook of a tire by promoting a glossiness of a surface of a molded tire, a surface of a mold is formed by shooting beads of a predetermined particle size and a tire surface a surface roughness (Ra) of which falls in a range of 1.5 through 20 μm is molded by using the mold. Further, US 2003/0230370 A1 (reference 4) discloses that in order to provide a light reflecting face along an outer surface of a tire, a side wall portion of the tire is molded by using a mold having an average surface roughness less than 0.381 μm.
Although according to technologies disclosed in references 3 and 4 mentioned above, the glossiness of the tire side portion is promoted by rectifying the roughness of the mold surface, the mold surface is adhered with a substance bloomed from inside of rubber constituting a tire main body in vulcanizing and molding the tire and is stained thereby. Therefore, there poses a problem that the outlook is deteriorated by transcribing the stain onto the surface of the side portion.
On the other hand, according to technologies disclosed in references 1 and 2 mentioned above, the resin film is provided at the outer surface of the tire side portion. However, the film is to be completely adhered to the tire main body, that is, the film constitutes a portion of the tire outer surface in using the tire, thereby, the weather resistance and the ozone crack resistance are promoted. Therefore, for example, according to reference 1, in order to firmly adhere the nylon film layer to the side wall rubber layer, the nylon film is subjected to a pretreatment of adherence of RFL (resorcinol formaldehyde latex) treatment or the like. Therefore, the technologies do not intend to provide the resin film on the tire outer surface to be able to be exfoliated therefrom.
Meanwhile, according to a pneumatic tire, there is a case in which a long period of time is taken after fabrication thereof until delivery to an end user. In such a case, in storage or in exhibition at a shop front thereof, it is necessary to prevent a commercial value from being deteriorated by ensuring weather resistance. With regard to the weather resistance, JP-A-2006-143889 (KOKAI) proposes to blend benzoate species and/or triazine species ultraviolet ray absorbing agent in a rubber composition for a tire along with diamine species antiaging agent in order to beautifully maintaining an outlook of the tire over a long period of time. However, the reference only discloses that the rubber per se constituting the tire main body is blended with the ultraviolet ray absorbing agent at a tire side portion or a tread portion.